I've downloaded the C# Facebook SDK "Simple MVC Website Example" from CodePlex at:
http://facebooksdk.codeplex.com/releases/view/54371
and have successfully got it to authenticate to my test Facebook app. But I can't quite work out how to get the access token (and I'm going to want offline access, so I only need to grab that token once, when the user first authorizes my app to grab their feed data).
Many thanks
You will want to do two things. First, to request offline_access, you need to change the Javascript login function to request offline access as follows. This is in the Views/Home/Index.aspx.
Next, to get the access token, you just do the following in action after the user is authenticated:
My recommendation is that you work with the new graph api instead, you can get it here
http://github.com/facebook/csharp-sdk
here's a description on how you fetch the authentication token:
http://developers.facebook.com/docs/authentication/